1. Field of Invention
The disclosure relates to phosphorus-containing bisphenols. More particularly, the disclosure relates to phosphorus-containing bisphenols with reactive functional groups and the methods of preparing thereof.
2. Description of Related Art
Since ancient times, fire accidents have always been a threat to human safety and cause economical damage. Various flame retardant materials are adapted to different applications; therefore the choice of the flame retardant materials should be based on the actual needs. Recently, the halogenated flame retardant compounds have been used as typical components of flame-retardant composites. However, the generations of corrosive and toxic substance (such as dioxin) from the halogenated flame retardants can cause metabolic disorder syndromes such as nervous, sleep disorders, headaches, eye disease, arteriosclerosis, liver tumors, and so on. Moreover, the relationship between the toxic substances and cancer has been reported in animal experiment.
In recent years, the organic phosphorus compounds that can provide good flame retardant properties for polymers have been investigated. In case of fire situation, the organic phosphorus-based polymers will not produce toxic gases. Furthermore, the organic phosphorus-based polymers provide advantages in processability, less usage amount and less release of smoke as compared to the halogenated flame-retardants. Particularly, an organic phosphorus-based polymer with reactive functional groups in the main structure will exhibit more flame-retardant effect.
DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) is a phosphorus-containing compound with active atomic hydrogen that can react with electron-deficient compounds, such as benzoquinone, oxirane, maleic acid, bismaleimide, diaminobenzophenone, and terephthaldicarboxaldehyde. The derivatives of DOPO are already attracting greater attention from researchers of the academic and industrial field.
In the early 1990s, a compound DOPOBQ was synthesized by reacting DOPO with benzoquinone has a formula represented as follow:

DOPOBQ is used as a precursor of bisphenol monomer to form bisphenol-based resin. However, the industrial applications are limited by its poor solubility and reactivity and high cost of the starting materials of DOPO.